There is provided an electrically controllable birefringence liquid crystal display (ecb-LCD) device, including: a liquid crystal panel including a first substrate, a second substrate, and a liquid crystal cell interposed between the first substrate and the second substrate and including a liquid crystal having positive dielectric anisotropy, the liquid crystal cell having a cell gap of 1 to 5 μm and operating in an ecb mode; a first polarizer disposed on an upper portion of the first substrate and having a first absorption axis; a second polarizer disposed on a lower portion of the second substrate and having a second absorption axis; a first liquid crystal film interposed between the first substrate and the first polarizer; and a second liquid crystal film interposed between the second substrate and the second polarizer; wherein the first liquid crystal film includes a first base substrate; and a first liquid crystal layer formed on a surface of the first base substrate and including a nematic liquid crystal splay-aligned such that a maximum tilt angle is 20° to 90° from an in-plane direction to a thickness direction; and wherein the second liquid crystal film includes a second base substrate; and a second liquid crystal layer formed on a surface of the second base substrate and including a horizontally aligned nematic liquid crystal.
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1. An electrically controllable birefringence liquid crystal display (ecb-LCD) device, comprising:
a liquid crystal panel including a first substrate, a second substrate, and a liquid crystal cell interposed between the first substrate and the second substrate and including a liquid crystal having positive dielectric anisotropy, the liquid crystal cell having a cell gap of 1 to 5 μm and operating in an ecb mode;
a first polarizer disposed on an upper portion of the first substrate and having a first absorption axis;
a second polarizer disposed on a lower portion of the second substrate and having a second absorption axis;
a first liquid crystal film interposed between the first substrate and the first polarizer; and
a second liquid crystal film interposed between the second substrate and the second polarizer;
wherein the first liquid crystal film includes a first base substrate; and a first liquid crystal layer formed on a surface of the first base substrate and including a nematic liquid crystal splay-aligned such that a maximum tilt angle is 20° to 90° from an in-plane direction to a thickness direction; and
wherein the second liquid crystal film includes a second base substrate; and a second liquid crystal layer formed on a surface of the second base substrate and including a horizontally aligned nematic liquid crystal,
wherein axes of the first base substrate and the first liquid crystal layer form an angle of 40° to 80° or −40° to −80°.
20. An electrically controllable birefringence liquid crystal display (ecb-LCD) device, comprising:
a liquid crystal panel including a first substrate, a second substrate, and a liquid crystal cell interposed between the first substrate and the second substrate and including a liquid crystal having positive dielectric anisotropy, the liquid crystal cell having a cell gap of 1 to 5 μm and operating in an ecb mode;
a first polarizer disposed on an upper portion of the first substrate and having a first absorption axis;
a second polarizer disposed on a lower portion of the second substrate and having a second absorption axis;
a first liquid crystal film interposed between the first substrate and the first polarizer; and
a second liquid crystal film interposed between the second substrate and the second polarizer;
wherein the first liquid crystal film includes a first base substrate made of a uniaxial retardation film having an in-plane retardation value of 200 nm to 300 nm at a wavelength of 550 nm; and a first liquid crystal layer including a nematic liquid crystal splay-aligned on the first base substrate such that a maximum tilt angle is 20° to 90° from an in-plane direction to a thickness direction, and having an optical axis which forms an angle of 40° to 80° or −40° to −80° with respect to an optical axis of the first base substrate and an in-plane retardation value of 50 nm to 150 nm; and
wherein the second liquid crystal film includes a second base substrate made of a uniaxial retardation film having an in-plane retardation value of 200 nm to 300 nm at a wavelength of 550 nm; and a second liquid crystal layer including a horizontally aligned nematic liquid crystal on the second base substrate, and having an optical axis which forms an angle of 40° to 80° or −40° to −80° with respect to an optical axis of the second base substrate and an in-plane retardation value of 50 nm to 150 nm.
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This application is a National Stage Entry of International Application No. PCT/KR2011/005241, filed Jul. 15, 2011, and claims the benefit of Korean Application No. 10-2010-0068704, filed on Jul. 15, 2010, which is hereby incorporated by reference in its entirety for all purposes as if fully set forth herein.
The present invention relates to a translucent reflective type electrically controllable birefringence liquid crystal display (ECB-LCD), and more particularly, to an ECB-LCD having a superior viewing angle and color characteristics and incurring low production costs.
An ECB-LCD is a liquid crystal display electrically controlling the birefringence of a liquid crystal, and, according to the related art, is formed as a translucent reflective type unit including a transmitting unit and a reflecting unit. The transmitting unit is configured such that a screen may be seen using a backlight in dark environments, while the reflecting unit is configured such that a screen may be seen using external light in bright environments.
The translucent reflective type LCD as described above is configured such that light moves through the same light path in both a transmitting mode and a reflecting mode. To this end, an achromatic quarter wave film (AQWF) is attached between a liquid crystal panel and a polarizing plate. In this case, the achromatic quarter wave film may be formed by combining two retardation films having different phase difference values and optical axes, and the two retardation films are attached to each other such that the optical axes thereof form an angle of approximately 30° to 80°.
However, in the case of an ECB-LCD according to the related art, the retardation film attached to a polarizing plate disposed towards a light source and the retardation film attached to a polarizing plate disposed towards a viewer may respectively form different angles, and an angle between the retardation films may be very large. Therefore, when the polarizing plate is manufactured by being formed as a single plate, defects, resulting in a large loss rate of the films, a high fault rate due to a complicated manufacturing process, and high manufacturing costs have been caused.
In the related art, retardation films are generally manufactured such that the optical axes thereof are directed in a vertical direction, and each retardation film is cut at an angle formed by a polarizing plate and the optical axis of the retardation film. The cut retardation films are combined to be manufactured. For example, when a first retardation film (λ/2) forms an angle of 15° and a second retardation film (λ/4) forms an angle of 75°, with respect to an absorption axis of a polarizing plate, the two films are cut such that the optical axes thereof respectively form angles of 15° and 75° with respect to the absorption axis of the polarizing plate. In this case, since the cutting angles, with respect to the absorption axis of the polarizing plate, are respectively 15° and 75°, a large loss rate of the films may be generated, thereby causing an increase in raw material expenses and manufacturing costs.
An aspect of the present invention provides an ECB-LCD having excellent viewing angle characteristics and color characteristics while being easily manufactured and incurring low manufacturing costs due to a simple structure thereof.
According to an aspect of the present invention, there is provided an electrically controllable birefringence liquid crystal display (ECB-LCD) device, including: a liquid crystal panel including a first substrate, a second substrate, and a liquid crystal cell interposed between the first substrate and the second substrate and including a liquid crystal having positive dielectric anisotropy, the liquid crystal cell having a cell gap of 1 to 5 μm and operating in an ECB mode; a first polarizer disposed on an upper portion of the first substrate and having a first absorption axis; a second polarizer disposed on a lower portion of the second substrate and having a second absorption axis; a first liquid crystal film interposed between the first substrate and the first polarizer; and a second liquid crystal film interposed between the second substrate and the second polarizer; wherein the first liquid crystal film includes a first base substrate; and a first liquid crystal layer formed on a surface of the first base substrate and including a nematic liquid crystal splay-aligned such that a maximum tilt angle is 20° to 90° from an in-plane direction to a thickness direction; and wherein the second liquid crystal film includes a second base substrate; and a second liquid crystal layer formed on a surface of the second base substrate and including a horizontally aligned nematic liquid crystal.
The first base substrate or the second base substrate may be a uniaxial retardation film, a negative biaxial retardation film, or an isotropic film. The uniaxial retardation film may be one selected from a group consisting of a uniaxially stretched cyclo olefin polymer (COP) film, a uniaxially stretched polycarbonate (PC) film, and a uniaxially stretched acrylate film. The negative biaxial retardation film may be one selected from a group consisting of a biaxially stretched COP film, a uniaxially stretched triacetyl cellulose (TAC) film, a biaxially stretched polycarbonate (PC) film and a biaxially stretched poly methyl methacrylate (PMMA) film. The isotropic film may one selected from a group consisting of a non-stretched COP film, a non-stretched acrylate film, and a non-stretched PMMA film.
Meanwhile, in the case of using the uniaxial retardation film as the first base substrate and/or the second substrate, the uniaxial retardation film may have an in-plane retardation value of approximately 200 nm to 300 nm at a wavelength of 550 nm.
In addition, in the case of using the negative biaxial retardation film as the first base substrate and/or the second substrate, the negative biaxial retardation film may have an in-plane retardation value of approximately 200 nm to 300 nm and a thickness direction retardation value of approximately −5 nm to −100 nm at a wavelength of 550 nm.
Meanwhile, an in-plane retardation value of the first liquid crystal layer may be approximately 50 nm to 150 nm, and an in-plane retardation value of the second liquid crystal layer may be approximately 50 nm to 150 nm.
In this case, axes of the first base substrate and the first liquid crystal layer may form an angle of 40° to 80° or −40° to −80°. Axes of the second base substrate and the second liquid crystal layer may form an angle of 40° to 80° or −40° to −80°.
Meanwhile, an alignment layer may be further included between the first base substrate and the first liquid crystal layer and/or the second base substrate and the second liquid crystal layer. In this case, the alignment layer may be an acrylic alignment layer or a photo alignment layer including polynorbornene-based cyanate or polyimide-based cyanate.
Meanwhile, an inner protective film may be inserted between the first polarizer and the first liquid crystal film and between the second polarizer and the second liquid crystal film.
According to another aspect of the present invention, there is provided a An electrically controllable birefringence liquid crystal display (ECB-LCD) device, comprising: a liquid crystal panel including a first substrate, a second substrate, and a liquid crystal cell interposed between the first substrate and the second substrate and including a liquid crystal having positive dielectric anisotropy, the liquid crystal cell having a cell gap of 1 to 5 μm and operating in an ECB mode; a first polarizer disposed on an upper portion of the first substrate and having a first absorption axis; a second polarizer disposed on a lower portion of the second substrate and having a second absorption axis; a first liquid crystal film interposed between the first substrate and the first polarizer; and a second liquid crystal film interposed between the second substrate and the second polarizer; wherein the first liquid crystal film includes a first base substrate made of a uniaxial retardation film having an in-plane retardation value of 200 nm to 300 nm at a wavelength of 550 nm; and a first liquid crystal layer including a nematic liquid crystal splay-aligned on the first base substrate such that a maximum tilt angle is 20° to 90° from an in-plane direction to a thickness direction, and having an optical axis which forms an angle of 40° to 80° or −40° to −80° with respect to an optical axis of the first base substrate and an in-plane retardation value of 50 nm to 150 nm; and wherein the second liquid crystal film includes a second base substrate made of a uniaxial retardation film having an in-plane retardation value of 200 nm to 300 nm at a wavelength of 550 nm; and a second liquid crystal layer including a horizontally aligned nematic liquid crystal on the second base substrate, and having an optical axis which forms an angle of 40° to 80° or −40° to −80° with respect to an optical axis of the second base substrate and an in-plane retardation value of 50 nm to 150 nm.
Meanwhile, an inner protective film may be inserted between the first polarizer and the first liquid crystal film and between the second polarizer and the second liquid crystal film.
An ECB-LCD according to the present invention could have a simple structure to allow for easy manufacturing thereof, have a superior competitive price due to incurring low manufacturing costs, and have superior viewing angle and color characteristics, as compared to that of the related art.
Hereinafter, the present invention will be explained in detail with reference to the drawings.
Respective components of the ECB-LCD according to the present invention will be described in detail.
(1) Liquid Crystal Panel 10
The liquid crystal panel 10 according to the present invention is a translucent reflective type liquid crystal panel operating in an ECB mode, and is not particularly limited, as long as it is a translucent reflective type liquid crystal panel operating in a general ECB mode.
For example, the liquid crystal panel according to the present invention may include a first substrate 12 and a second substrate 16 disposed to be opposed to each other while having a predetermined interval therebetween, and a liquid crystal cell 14 interposed between the first substrate 12 and the second substrate 16. In this case, the first substrate 12 and the second substrate 16 may be provided with driving elements for driving the liquid crystal cell, such as electrodes. The liquid crystal cell 14 may have a liquid crystal having positive dielectric anisotropy (Δ∈>0) injected thereinto, and a gap in the liquid crystal cell 14 may be approximately 1 to 5 μm.
(2) First Polarizer 20 and Second Polarizer 30
The first polarizer 20 is disposed on an upper portion of the first substrate 12 of the liquid crystal panel 10 and the second polarizer 30 is disposed on a lower portion of the second substrate 16 of the liquid crystal panel 10. The first polarizer 20 and the second polarizer 30 may realize light and shade by transmitting or blocking light polarized in a specific direction, according to the driving of the liquid crystal cell 14. In general, an absorption axis of the first polarizer and an absorption axis of the second polarizer are disposed to form an angle of 80° to 120°.
Meanwhile, in the present invention, the respective first polarizer 20 and the second polarizer 30 may be formed of only a polarizing film without a protective film, or may include protective film(s) attached to a surface or two surface thereof. In this case, as the protective film, a protective film generally used in the related art may be used, for example, a TAC film, a PE film, a PET film, or the like.
(3) First Liquid Crystal Film 40 and Second Liquid Crystal Film 50
The first liquid crystal film 40 and the second liquid crystal film 50 are compensation films for compensating for viewing angle and color characteristics of the ECB-LCD, simultaneously with implementing a translucent reflection function. The translucent reflection function may be implemented by combining a λ/2 retardation plate and a λ/4 retardation plate. Meanwhile, in the case of an ECB-LCD, viewing angle characteristics may be degraded due to light leakage at a tilt angle in a dark state. The light leakage may be generated due to the liquid crystal cell and the polarizing plate not being in an orthogonal state at the tilt angle. When the light leakage is generated, a contrast ratio may be degraded and color changes may be caused to thereby lead to degradation in viewing angle characteristics. Thus, in the present invention, the first liquid crystal film 40 and the second liquid crystal film 50, capable of performing a viewing angle compensation function, are inserted between the respective polarizer and the liquid crystal cell, such that the above-defects are resolved.
In the present invention, two types of liquid crystal films are used. One liquid crystal film inserted between the first polarizer and the first substrate refers to a first liquid crystal film and the other liquid crystal film inserted between the second polarizer and the second substrate refers to a second liquid crystal film, for convenience.
First, the first liquid crystal film 40 will be explained. As described above, the first liquid crystal film 40 may be interposed between the first substrate 12 and the first polarizer 20, and be formed of a first base substrate 42 and a first liquid crystal layer 44 formed on a surface of the first base substrate 42.
In this case, the first base substrate 42 may be made of any one of a positive uniaxial retardation film, a negative biaxial retardation film, and an isotropic film. Meanwhile, the positive uniaxial retardation film refers to a film satisfying nx>ny=nz; the negative biaxial retardation film refers to a film satisfying nx>ny>nz,; and the isotropic film refers to a film satisfying nx=ny=nz, provided that a refractive index in x-axis direction is n, a refractive index in y-axis direction is ny, and a refractive index in z-axis direction is nz.
In this case, as the uniaxial retardation film, for example, a uniaxially stretched cyclo olefin polymer (COP) film, a uniaxially stretched polycarbonate (PC) film, or a uniaxially stretched acrylate film may be used. In the case of using the uniaxial retardation film as the first base substrate, the uniaxial retardation film may have an in-plane retardation value of approximately 200 nm to 300 nm at a wavelength of 550 nm.
Meanwhile, as the biaxial retardation film, for example, a biaxially stretched COP film, a uniaxially stretched triacetyl cellulose (TAC) film, a biaxially stretched polycarbonate (PC) film or a biaxially stretched poly methyl methacrylate (PMMA) film may be used. In the case of using the biaxial retardation film as the first base substrate, the biaxial retardation film may have an in-plane retardation value of approximately 200 nm to 300 nm and a thickness direction retardation value of approximately −5 nm to −100 nm at a wavelength of 550 nm.
As the isotropic film, for example, a non-stretched COP film, a non-stretched acrylate film, or a non-stretched PMMA film may be used.
Meanwhile, the first liquid crystal layer 44 may be formed such that a nematic liquid crystal is splay-aligned on the first base substrate 42. In the case of the splay aligned nematic liquid crystal, since a director is consecutively changed in a thickness direction, parameters capable of defining an alignment of the liquid crystal director may be required. The first liquid crystal layer may be defined as the following [Equation 1], provided that a pretilt angle of the splay aligned nematic liquid crystal refers to θ1, a maximum tilt angle thereof refers to θ2, a director profile coefficient describing the nematic liquid crystal distribution between the pretilt angle and the maximum tilt angle refers to α, and the liquid crystal layer is formed of N layers having different director distributions.
θ(i)=(d×i/N)α×(θ2−θ1)+θ1 [Equation 1]
Where, θ(i) indicating a tilt angle change according to thickness, refers to a tilt angle distribution at an ith layer when the liquid crystal layer is divided into N layers from 0 to d. For example, θ(3) refers to a tilt angle distribution at a 3th layer when the liquid crystal layer is divided into N layers.
In [Equation 1], when a is 1, the liquid crystal director distribution (tilt angle distribution of liquid crystal molecules) may show a constant linear distribution. When α is less than 1, it can be seen that the liquid crystal director distribution initially smoothly increases and rapidly changes in the vicinity of a maximum tilt angle. When α is more than 1, it can be seen that the liquid crystal director distribution initially rapidly changes and then smoothly changes in the vicinity of the maximum tilt angle.
The liquid crystal director distribution may refer to an important value determining optical characteristics of a viewing angle compensation film in the ECB-LCD and determining an optical axis at each viewing angle as well as a retardation distribution according the angle.
Meanwhile, in the present invention, the first liquid crystal layer may be splay-aligned such that a maximum tilt angle θ2 is 20° or more, preferably approximately 20° to 90° from an in-plane direction to a thickness direction, in a liquid crystal tilt angle. Since the maximum tilt angle is less than 20°, viewing angle compensation functions may be insignificant.
In addition, the first liquid crystal layer may be splay-aligned such that an average tilt angle is 35° or more, preferably 35° to 90°. In this case, the average tilt angle refers to an average value of a pretilt angle, an intermediate tilt angle, and a maximum tilt angle. For instance, when a liquid crystal film coated with a thickness of 1 um is divided into three layers, an average tilt angle satisfies (2+3+4+5)/4=3.5°, provided that a pretilt angle is 2°, a tilt angle of a first layer is 3°, a tilt angle of a second layer is 4°, and a tilt angle of a third layer is 5°. The average tilt angle is less than 35°, ECB viewing angle compensation functions may be significantly degraded.
In addition, the first liquid crystal layer may have an in-plane retardation value of approximately 50 nm to 150 nm, and an angle formed by an optical axis of the first base substrate and an optical axis of the first liquid crystal layer may be approximately 40° to 80° or −40° to −80°. When the in-plane retardation value of the first liquid crystal layer and the optical axes thereof satisfy the above numerical ranges, the function of an achromatic quarter wave film (AQWF) may be smoothly performed.
In this case, an in-plane retardation value (Rin) refers to a value defined as in the following [Equation 2]:
Rin=d×(nx−ny) [Equation 2]
Where d refers to a thickness of the liquid crystal layer, nx refers to a refractive index in x-axis direction, and ny refers to a refractive index in y-axis direction.
Next, the second liquid crystal film 50 will be explained. The second liquid crystal film 50 may be interposed between the second substrate 16 and the second polarizer 30 and be formed of a second substrate 52 and a second liquid crystal layer 54 formed on a surface of the second substrate 52.
In this case, similarly to the first base substrate 42, the second base substrate 52 may be formed of any one of a positive uniaxial film, a negative biaxial film, and an isotropic film. The detailed description of the positive uniaxial film, the negative biaxial film, and the isotropic film is identical to the description thereof as in the first base substrate.
Meanwhile, the second liquid crystal layer 54 is formed of horizontally aligned nematic liquid crystals and has a positive in-plane retardation value. The in-plane retardation value of the second liquid crystal layer 54 may be varied depending on types of the second base substrate, or the like, but may be approximately 50 nm to 150 nm.
The optimum retardation value with which the achromatic quarter wave film is fabricated may be slightly varied, based on the base substrate; however, the range of the retardation value in which the achromatic quarter wave film is fabricated is 50 nm to 150 nm, and substantially unvaried.
In this case, an angle formed by an optical axis in an in-plane direction of the second base substrate and an optical axis of the second liquid crystal layer may be ±40° to ±80°.
Meanwhile, each of the first liquid crystal film and the second liquid crystal film may further include an alignment layer between the base substrate and the liquid crystal layer thereof, the alignment layer imparting alignment to the liquid crystal layer. For convenience, an alignment layer inserted between the first base substrate and the first liquid crystal layer refers to a first alignment layer, and an alignment layer inserted between the second base substrate and the second liquid crystal layer refers to a second alignment layer. As the first alignment layer and/or the second alignment layer, an alignment layer generally used in the related art may be used, for example, a rubbing alignment layer or a photo alignment layer. More specifically, a rubbing alignment layer, such as an acrylic alignment layer, a photo alignment layer including polynorbornene-based cyanate or polyimide-based cyanate, or the like may be used.
In the case of the ECB-LCD configured as above, according to the present invention, since a liquid crystal film having a liquid crystal layer formed on a base substrate film is used as a compensation film, a process of matching angles of two retardation films and combining the retardation films as in the related art may not be required. As a result, the ECB-LCD according to the present invention may be easily manufactured and manufacturing costs thereof may be low, as compared to the case in the related art. In addition, the ECB-LCD configured as above according to the present invention may have excellent viewing angle and color characteristics, as compared to the ECB-LCD according to the related art.
Hereafter, the present invention will be explained in detail through concrete Examples.
The front contrast ratio and viewing angle characteristics of an ECB-LCD having a backlight, a first polarizer, a first inner protective film, a first liquid crystal film, an ECB-LCD panel, a second liquid crystal film, a second inner protective film and a second polarizer sequentially arranged in order were measured based on base substrates of the first liquid crystal film and the second liquid crystal film and in-plane retardation values of the liquid crystal layers thereof.
In this case, as the first inner protective film, a TAC film having a thickness of 50 μm and a thickness direction retardation value of −30 nm was used. As the first liquid crystal film, a uniaxially stretched COP film (first base substrate) on which a liquid crystal was splay-aligned and of which a thickness was 270 nm was used. In this case, the first polarizer and an optical axis of the first base substrate were disposed so as to form an angle of −15°, and the optical axis of the first base substrate and an optical axis of the first liquid crystal layer were disposed so as to form an angle of 60°.
In addition, as the second inner protective film, a TAC film having a thickness of 50 μm and a thickness direction retardation value of −30 nm was used. As the second liquid crystal film, a uniaxially stretched COP film (second base substrate) on which a nematic liquid crystal was horizontally aligned and of which a thickness was 270 nm was used. In this case, the second polarizer and an optical axis of the second base substrate were disposed so as to form an angle of 67.5°, and the optical axis of the second base substrate and an optical axis of the second liquid crystal layer are disposed so as to form an angle of −67.5°.
Meanwhile, a retardation value of a liquid crystal cell of the ECB-LCD panel was 330 nm, and the retardation value was measured using a wavelength of 550 nm.
The measured results are shown in the following [Table 1-1] to [Table 1-5]. Meanwhile,
TABLE 1-1
First base
First liquid
Second base
Second liquid
Front Contrast
Viewing angle
substrate
crystal layer
substrate
crystal layer
Rate (CR)
Top
Bottom
Left
Right
270
110
270
100
78
60
70
60
50
270
110
270
105
132
60
80
70
52
270
110
270
110
208
62
80
80
58
270
110
270
115
252
65
80
80
60
270
110
270
120
198
65
80
80
60
270
115
270
100
133
62
78
65
55
270
115
270
105
208
64
80
75
57
270
115
270
110
250
68
80
80
58
270
115
270
115
198
68
80
80
60
270
115
270
120
129
70
80
80
60
270
120
270
100
133
62
78
65
55
270
120
270
105
208
64
80
75
57
270
120
270
110
250
86
80
80
58
270
120
270
115
198
88
80
80
60
270
120
270
120
129
70
80
80
60
TABLE 1-2
First base
First liquid
Second base
Second liquid
Front Contrast
Viewing angle
substrate
crystal layer
substrate
crystal layer
Rate (CR)
Top
Bottom
Left
Right
270
110
275
100
56
47
62
49
68
270
110
275
105
92
48
66
53
71
270
110
275
110
158
51
71
57
77
270
110
275
115
244
52
76
59
80
270
110
275
120
260
56
80
62
80
270
115
275
100
91
48
73
51
74
270
115
275
105
155
50
80
54
77
270
115
275
110
242
53
80
58
80
270
115
275
115
262
55
80
61
80
270
115
275
120
185
56
80
65
80
270
120
275
100
153
50
80
54
79
270
120
275
105
241
53
80
56
80
270
120
275
110
262
55
80
58
80
270
120
275
115
187
57
80
62
80
270
120
275
120
115
58
80
66
80
TABLE 1-3
First base
First liquid
Second base
Second liquid
Front Contrast
Viewing angle
substrate
crystal layer
substrate
crystal layer
Rate (CR)
Top
Bottom
Left
Right
265
110
265
100
144
60
80
77
56
265
110
265
105
224
64
80
80
60
265
110
265
110
249
67
80
80
63
265
110
265
115
180
69
80
80
63
265
110
265
120
114
72
80
80
65
265
115
265
100
223
62
80
80
60
265
115
265
105
249
55
80
80
62
265
115
265
110
184
58
80
80
84
265
115
265
115
116
71
80
80
65
265
115
265
120
74
74
80
80
86
265
120
265
100
249
64
80
80
62
265
120
265
105
186
67
80
80
84
265
120
265
110
118
70
80
80
66
265
120
265
115
75
73
80
80
67
265
120
265
120
51
78
80
80
88
TABLE 1-4
First base
First liquid
Second base
Second liquid
Front Contrast
Viewing angle
substrate
crystal layer
substrate
crystal layer
Rate (CR)
Top
Bottom
Left
Right
270
110
275
100
56
53
77
62
48
270
110
275
105
91
57
80
67
48
270
110
275
110
152
61
80
73
53
270
110
275
115
231
66
80
79
55
270
110
275
120
242
68
80
80
56
270
115
275
100
90
55
80
75
50
270
115
275
105
150
59
80
80
53
270
115
275
110
230
63
80
80
55
270
115
275
115
242
66
80
80
57
270
115
275
120
175
69
80
80
58
270
120
275
100
149
58
80
80
52
270
120
275
105
228
61
80
80
54
270
120
275
110
244
65
80
80
57
270
120
275
115
177
66
80
80
58
270
120
275
120
112
70
80
80
50
TABLE 1-5
First base
First liquid
Second base
Second liquid
Front Contrast
Viewing angle
substrate
crystal layer
substrate
crystal layer
Rate (CR)
Top
Bottom
Left
Right
275
110
275
100
45
50
71
59
46
275
110
275
105
72
55
78
65
48
275
110
275
110
110
58
80
68
50
275
110
275
115
134
61
80
76
54
275
110
275
120
250
65
80
80
55
275
115
275
100
70
53
78
71
47
275
115
275
105
117
57
80
76
51
275
115
275
110
191
60
80
80
54
275
115
275
115
251
64
80
80
54
275
115
275
120
213
68
80
80
57
275
120
275
100
145
55
77
80
50
275
120
275
105
189
58
78
80
53
275
120
275
110
251
62
80
80
55
275
120
275
115
214
65
80
80
57
275
120
275
120
140
68
80
80
58
The front contrast ratio and viewing angle characteristics of an ECB-LCD having a backlight, a first polarizer, a first liquid crystal film, an ECB-LCD panel, a second liquid crystal film, and a second polarizer sequentially arranged in order were measured based on base substrates of the first liquid crystal film and the second liquid crystal film and in-plane retardation values of the liquid crystal layers thereof.
In this case, as the first liquid crystal film, a uniaxially stretched COP film (first base substrate) on which a liquid crystal was splay-aligned (first liquid crystal layer) and of which a thickness was 270 nm was used. In this case, the first base substrate was disposed such that an optical axis thereof forms an angle of 67.5°, with respect to an absorption axis of the first polarizer, and an optical axis of the first liquid crystal layer was disposed to be identical to the absorption axis of the first polarizer.
In addition, as the second liquid crystal film, a uniaxially stretched COP film (second base substrate) on which a nematic liquid crystal was horizontally aligned (second liquid crystal layer) and of which a thickness was 270 nm was used. In this case, the second base substrate was disposed such that an optical axis thereof forms an angle of 15° with respect to an absorption axis of the second polarizer, and the second liquid crystal layer was disposed such that an optical axis thereof forms an angle of 60° with respect to the optical axis of the second base substrate.
Meanwhile, a retardation value of a liquid crystal cell of the ECB-LCD panel was 330 nm, and the retardation value was measured using a wavelength of 550 nm.
The measured results are shown in the following [Table 2-1] to [Table 2-7]. Meanwhile,
TABLE 2-1
First base
First liquid
Second base
Second liquid
Front Contrast
Viewing angle
substrate
crystal layer
substrate
crystal layer
Rate (CR)
Top
Bottom
Left
Right
270
110
270
100
76
49
68
51
69
270
110
270
105
129
52
75
54
73
270
110
270
110
211
54
79
58
78
270
110
270
115
270
57
80
61
80
270
110
270
120
214
58
80
64
80
270
115
270
100
128
52
80
54
75
270
115
270
105
212
54
80
57
79
270
115
270
110
271
57
80
59
80
270
115
270
115
217
57
80
62
80
270
115
270
120
136
59
80
65
80
270
120
270
100
203
54
80
55
73
270
120
270
105
269
56
80
58
80
270
120
270
110
220
57
80
60
80
270
120
270
115
138
59
80
65
80
270
120
270
120
86
60
80
67
80
TABLE 2-2
First base
First liquid
Second base
Second liquid
Front Contrast
Viewing angle
substrate
crystal layer
substrate
crystal layer
Rate (CR)
Top
Bottom
Left
Right
270
110
275
100
56
47
62
49
68
270
110
275
105
92
48
86
53
71
270
110
275
110
158
51
71
57
77
270
110
275
115
244
52
76
59
80
270
110
275
120
260
56
80
62
80
270
115
275
100
91
48
73
51
74
270
115
275
105
155
50
80
54
77
270
115
275
110
242
53
80
58
80
270
115
275
115
262
55
80
61
80
270
115
275
120
165
56
80
65
80
270
120
275
100
153
50
80
54
79
270
120
275
105
241
53
80
56
80
270
120
275
110
262
55
80
58
80
270
120
275
115
187
57
60
62
80
270
120
275
120
115
58
60
66
80
TABLE 2-3
First base
First liquid
Second base
Second liquid
Front Contrast
Viewing angle
substrate
crystal layer
substrate
crystal layer
Rate (CR)
Top
Bottom
Left
Right
275
110
275
100
45
44
59
47
64
275
110
275
105
72
48
63
50
69
275
110
275
110
121
49
68
54
73
275
110
275
115
203
51
72
57
77
275
110
275
120
270
54
76
60
80
275
115
275
100
71
47
68
48
70
275
115
275
105
118
49
75
52
74
275
115
275
110
200
51
80
56
77
275
115
275
115
269
54
80
58
80
275
115
275
120
227
55
80
62
80
275
120
275
100
118
48
80
51
74
275
120
275
105
196
51
80
54
77
275
120
275
110
268
53
80
57
79
275
120
275
115
229
55
80
60
80
275
120
275
120
147
57
80
65
80
TABLE 2-4
First base
First liquid
Second base
Second liquid
Front Contrast
Viewing angle
substrate
crystal layer
substrate
crystal layer
Rate (CR)
Top
Bottom
Left
Right
275
110
275
100
45
44
59
47
64
275
110
275
105
72
48
63
50
69
275
110
275
110
121
49
68
54
73
275
110
275
115
203
51
72
57
77
275
110
275
120
270
54
76
60
80
275
115
275
100
71
47
68
48
70
275
115
275
105
118
49
75
52
74
275
115
275
110
200
51
80
56
77
275
115
275
115
269
54
80
58
60
275
115
275
120
227
55
80
62
60
275
120
275
100
118
48
80
51
74
275
120
275
105
196
51
80
54
77
275
120
275
110
268
53
80
57
79
275
120
275
115
229
55
80
60
80
275
120
275
120
147
57
80
65
80
TABLE 2-5
First base
First liquid
Second base
Second liquid
Front Contrast
Viewing angle
substrate
crystal layer
substrate
crystal layer
Rate (CR)
Top
Bottom
Left
Right
265
110
265
100
136
56
80
55
75
265
110
265
105
233
57
80
59
78
265
110
265
110
267
58
80
61
80
265
110
265
115
205
60
80
65
80
265
110
265
120
127
62
80
68
80
265
115
265
100
223
57
80
57
80
265
115
265
105
288
58
80
59
80
265
115
265
110
208
59
80
63
80
265
115
265
115
129
62
80
65
80
265
115
265
120
81
64
80
66
80
265
120
265
100
270
59
80
58
80
265
120
265
105
209
60
80
61
80
265
120
265
110
130
62
80
64
80
265
120
265
115
82
64
80
67
80
265
120
265
120
54
65
80
69
80
TABLE 2-6
First base
First liquid
Second base
Second liquid
Front Contrast
Viewing angle
substrate
crystal layer
substrate
crystal layer
Rate (CR)
Top
Bottom
Left
Right
260
110
265
100
177
57
80
57
78
260
110
265
105
260
59
80
59
80
260
110
265
110
248
60
80
63
80
260
110
265
115
164
62
80
66
80
260
110
265
120
101
64
80
69
80
260
115
265
100
259
58
80
58
80
260
115
265
105
249
61
80
62
80
260
115
265
110
165
63
80
65
80
260
115
265
115
102
64
80
63
80
260
115
265
120
56
65
80
70
80
260
120
265
100
250
60
80
60
80
260
120
265
105
168
62
80
64
80
260
120
265
110
103
64
80
67
80
260
120
265
115
67
65
80
68
80
260
120
265
120
46
67
80
71
80
TABLE 2-7
First base
First liquid
Second base
Second liquid
Front Contrast
Viewing angle
substrate
crystal layer
substrate
crystal layer
Rate (CR)
Top
Bottom
Left
Right
260
110
260
100
235
60
80
58
80
260
110
260
105
267
62
80
62
80
260
110
260
110
195
64
80
65
80
260
110
260
115
120
65
80
68
80
260
110
260
120
76
67
80
71
80
260
115
260
100
268
62
80
59
80
260
115
260
105
197
65
80
64
80
260
115
260
110
122
65
80
67
80
260
115
260
115
77
68
80
69
80
260
115
260
120
52
68
80
71
80
260
120
260
100
188
64
80
62
80
260
120
260
105
124
67
80
65
80
260
120
260
110
78
68
80
67
80
260
120
260
115
52
68
80
70
80
270
120
260
120
37
63
80
74
80
For comparison, the front contrast ratio (CR) and viewing angle characteristics of an ECB-LCD in the case of using compensation films according to the related art were measured. In this case, as the compensation film disposed on an upper polarizing plate, a combination of a ½ wavelength plate having an in-plane retardation value of 270 nm and a ¼ wavelength plate having an in-plane retardation value of 110 nm was used. As the compensation film disposed under a lower polarizing plate, a combination of a ½ wavelength plate having an in-plane retardation value of 270 nm and a ¼ wavelength plate formed of a splay-aligned liquid crystal film was used. In the compensation film disposed on the upper polarizing plate, optical axes of the ½ wavelength plate and ¼ wavelength plate were disposed so as to form an angle of 60°. In the compensation film disposed under the lower polarizing plate, optical axes of the ½ wavelength plate and ¼ wavelength plate were disposed so as to form an angle of 67.5°.
The front contrast ratio (CR) of the ECB-LCD using the above compensation film according to the related art was 237:1, and the viewing angle characteristics thereof are shown in the following [Table 3].
TABLE 3
Upper polarizing
Upper polarizing
Lower polarizing
Lower polarizing
plate retardation
plate retardation
plate retardation
plate NR
Front contrast
Viewing angle
film 1
film 2
film 1
film 1
ratio (CR)
Top
Bottom
left
Right
270 nm
110 nm
270 nm
110 nm
237
58
80
72
80
As shown in the [Table 1] to [Table 3], the ECB-LCDs according to Examples 1 and 2 have optical characteristics equal to or greater than those of the ECB-LCD according to the Comparative Example, and allow for a reduction in manufacturing costs through minimized cutting loss due to integrating the retardation film and the liquid crystal film.
While the present invention has been shown and described in connection with the embodiments, it will be apparent to those skilled in the art that modifications and variations can be made without departing from the spirit and scope of the invention as defined by the appended claims.
Park, Moon-Soo, Jeon, Byoung-Kun, Ryu, Su-Young, Yoon, Sang-Jun
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